1. Field of the Invention
The present invention is related to an improved structure for foldable storage bins, and especially to an improved structure for storage bins which is structurally firmer after assembling. The structure includes tenons and slot mortises respectively provided for connecting of the side plates in order to prevent the side plates from falling down inwardly; and includes upright stop pieces on the four edges of a bottom board to prevent the side plates from falling down outwardly when the latter are placed upright thereon, thereby, stability of assembling of the side plates can be obtained; and includes an inner frame and an outer frame extending downwardly on the bottom board, so that when two storage bins are stacked with each other, the inner and outer frames on the upper storage bin form a groove to engage over the side plates of the lower storage bin to increase stability of stacking.
2. Description of the Prior Art
A conventional foldable storage bin comprises mainly a square bottom board with four side plates foldable inwardly and pivotably mounted on the four edges thereof; wherein, a pair of mutually opposite side plates each has on both ends thereof an abutting portion protruding inwardly and provided with a plurality of slot mortises, while the other pair of mutually opposite side plates each has on both ends thereof a plurality of corresponding tenons. Thereby, when all the side plates are assembled in their upright positions, the side plates with the abutting portions are abutted against the other pair of mutually opposite side plates, and engagement between all the slot mortises with their corresponding tenons forms a firm connecting structure. The side plates can all be folded down inwardly till the bottom board thereof. So that when the storage bin is not in use, the whole storage bin can be folded into a pile of stacked plates in favor of carrying and storage. However, connecting among the side plates is effected completely by abutment of the abutting portions and engagement between the slot mortises with their corresponding tenons, the storage bin not only is subjected to collapse by collision of an external force, but also is lack of supporting when each side plate is erected singly. While the four side plates cannot be erected at the same time, it is difficult to connect the four side plates mutually; it is unable to maintain good structure strength when the four side plates are stacked. Therefore, practicality of such a storage bin is far inferior to a fixed type storage bin. And this is the very point on that people in the art are eager for an improvement.